Project description:T cell dysfunction is an important feature of many chronic viral infections. In particular, it was shown that PD-1 regulates T cell dysfunction during chronic LCMV infection in mice and PD-1 high cells exhibit an intense exhausted gene signature. These findings were extended to human chronic infections such as HIV, HCV and HBV. However, it is not known if PD-1 high cells of healthy humans have the traits of exhausted cells. In this study, we provide a comprehensive description of phenotype, function and gene expression profiles of PD-1 high versus PD-1 low CD8 T cells in the peripheral blood of healthy human adults as following: 1) The percentage of naive and memory CD8 T cells varied widely in the peripheral blood cells of healthy humans and PD-1 was expressed by the memory CD8 T cells. 2) PD-1 high CD8 T cells in healthy humans did not significantly correlated with the PD-1 high exhausted gene signature of HIV specific human CD8 T cells or chronic LCMV specific CD8 T cells from mice. 3) PD-1 expression did not directly affect the ability of CD8 T cells to secrete cytokines in healthy adults. 4) PD-1 was expressed by the effector memory (TEM) compared to ‘terminally differentiated effector’ (TEMRA) CD8 T cells. 5) Finally, an interesting inverse relationship between CD45RA and PD-1 expression was observed. We used highly purified PD-1 high and PD-1 low from six healthy adult individuals and naive CD8 T cell populations from four of those individuals for gene expression studies
Project description:During acute viral infections, naïve CD8+ T cells differentiate into effector CD8+ T cells and, after viral control, into memory CD8+ T cells. Memory CD8+ T cells are highly functional, proliferate rapidly upon reinfection and persist long-term without antigen. In contrast, during chronic infections, CD8+ T cells become “exhausted” and have poor effector function, express multiple inhibitory receptors, possess low proliferative capacity, and cannot persist without antigen. To compare the development of functional memory T cells with poorly functional exhausted T cells, we generated longitudinal transcriptional profiles for each. Naive CD44Lo CD8+ T cells were isolated and sorted from uninfected C57BL/6 mice and H2-Db GP33-specific CD8+ T cells were sorted using MHC-I tetramers at d6, 8, 15, and 30 p.i. with either LCMV Arm or LCMV clone 13. RNA from these CD8+ T cells was processed, amplified, labeled, and hybridized to Affymetrix GeneChip MoGene 1.0 st microarrays
Project description:Chronic viral infections are characterized by a state of CD8 T cell dysfunction termed exhaustion. A better understanding of the mechanisms that regulate CD8 T cell responses during chronic infection is required to improve immunotherapies that restore function in exhausted CD8 T cells. Here we identify a novel population of virus-specific CD8 T cells with a T follicular helper (Tfh)-like signature in mice chronically infected with lymphocytic choriomeningitis virus (LCMV). These Tfh-like CD8 T cells expressed the programmed cell death-1 (PD-1) inhibitory receptor but at the same time also expressed co-stimulatory molecules and had a gene signature that was related to CD8 T cell memory precursor cells and hematopoietic stem cells (HSC). These Tfh-like CD8 T cells acted as stem cells during chronic infection undergoing self-renewal and also differentiating into the terminally exhausted CD8 T cells that were present in both lymphoid and non-lymphoid tissues. The Tfh-like CD8 T cells were found only in lymphoid tissues and resided predominantly in the T cell zones along with naïve CD8 T cells. Interestingly, the proliferative burst after PD-1 blockade came almost exclusively from this Tfh-like CD8 T cell subset. Importantly, the transcription factor TCF1 played a cell intrinsic and essential role in the generation of Tfh-like CD8 T cells. Taken together, our study identifies Tfh-like CD8 T cells as the critical subset for maintaining the pool of virus-specific CD8 T cells during chronic infection and as the cells that proliferate after PD-1 blockade. These findings provide a better understanding of T cell exhaustion and have implications towards optimizing PD-1 directed immunotherapy. 8 samples isolated from CD8 T-cells in LCMV clone 13 GK1.5 infected mice (2 naïve, 3 CXCR5+Tim3-, 3 CXCR5-Tim3+) cells were analyzed
Project description:During acute viral infections, naïve CD8+ T cells differentiate into effector CD8+ T cells and, after viral control, into memory CD8+ T cells. Memory CD8+ T cells are highly functional, proliferate rapidly upon reinfection and persist long-term without antigen. In contrast, during chronic infections, CD8+ T cells become “exhausted” and have poor effector function, express multiple inhibitory receptors, possess low proliferative capacity, and cannot persist without antigen. Exhuasted CD8+ T cells can be further segregated by their expression of the inhibitory cell surface receptor PD-1. We performed transcriptional profiling on both PD-1 High and PD-1 Intermediate H2-Db GP33-specific CD8+ T cells. H2-Db GP33-specific CD8+ T cells were sorted from C57BL/6 mice 30 days p.i. with LCMV clone 13. These cells were then segregated by their expression of the inhibitory cell surface receptor PD-1 into PD-1 High and PD-1 Intermediate subpopulations. We performed transcriptional profiling on these subpopulations.
Project description:In chronic infections and cancer, exhausted CD8 T cells exhibit heterogeneous subpopulations. TCF1+PD-1+ progenitor exhausted CD8 T cells (Tpex) can self-renew and give rise to Tim-3+PD-1+ terminally differentiated CD8 T cells that retain their effector functions. Tpex cells are thus essential to maintaining a pool of antigen-specific CD8 T cells during persistent antigenic stimulation, and only they respond to PD-1-targeted therapy. Despite their potential as a crucial therapeutic target for immune interventions, the mechanisms controlling the maintenance of virus-specific Tpex cells remain to be determined. We observed approximately 10-fold fewer Tpex cells in the spleens of mice chronically infected with lymphocytic choriomeningitis virus (LCMV) one-year post-infection (p.i.) than at three months p.i. Similar to memory CD8 T cells, Tpex cells have been found to undergo self-renewal in the lymphoid organs, prominently the bone marrow, during chronic LCMV infection. Furthermore, ex vivo treatment with IL-15 preferentially induced the proliferation of Tpex cells rather than the terminally differentiated subsets. Interestingly, single-cell RNA sequencing analysis of LCMV-specific exhausted CD8 T cells after ex vivo IL-15 treatment compared with those before treatment revealed upregulation of ribosome-related genes and downregulation of genes associated with the TCR signaling pathway and apoptosis in both Tpex and Ttex subsets. The exogenous administration of IL-15 to chronically LCMV-infected mice also significantly increased self-renewal of Tpex cells in the spleen and bone marrow. In addition, we assessed the responsiveness of CD8 tumor-infiltrating lymphocytes (TILs) from renal cell carcinoma patients to IL-15. Similar to the data we obtained from chronic viral infection in mice, the expansion of the Tpex subset of PD-1+ CD8 TILs upon ex vivo IL-15 treatment was significantly higher than that of the terminally differentiated subset. These results show that IL-15 could promote self-renewal of Tpex cells, which has important therapeutic implications.
Project description:T cell dysfunction is an important feature of many chronic viral infections. In particular, it was shown that PD-1 regulates T cell dysfunction during chronic LCMV infection in mice and PD-1 high cells exhibit an intense exhausted gene signature. These findings were extended to human chronic infections such as HIV, HCV and HBV. However, it is not known if PD-1 high cells of healthy humans have the traits of exhausted cells. In this study, we provide a comprehensive description of phenotype, function and gene expression profiles of PD-1 high versus PD-1 low CD8 T cells in the peripheral blood of healthy human adults as following: 1) The percentage of naive and memory CD8 T cells varied widely in the peripheral blood cells of healthy humans and PD-1 was expressed by the memory CD8 T cells. 2) PD-1 high CD8 T cells in healthy humans did not significantly correlated with the PD-1 high exhausted gene signature of HIV specific human CD8 T cells or chronic LCMV specific CD8 T cells from mice. 3) PD-1 expression did not directly affect the ability of CD8 T cells to secrete cytokines in healthy adults. 4) PD-1 was expressed by the effector memory (TEM) compared to ‘terminally differentiated effector’ (TEMRA) CD8 T cells. 5) Finally, an interesting inverse relationship between CD45RA and PD-1 expression was observed.
Project description:Lymphocytic choriomeningitis virus (LCMV) is the prototypic arenavirus and a natural mouse pathogen. LCMV Armstrong, an acutely resolved strain, and LCMV Clone 13, a mutant that establishes chronic infection, have provided contrasting infection models that continue to inform the fundamental biology of T cell differentiation, regulation of exhaustion, and response to checkpoint blockade. Here, we report the isolation and characterization of LCMV Minnesota (LCMV-MN), which was naturally transmitted to laboratory mice upon cohousing with pet shop mice and shares 80-95% amino acid homology with previously characterized LCMV strains. Infection of laboratory mice with purified LCMV-MN resulted in viral persistence that was intermediate between LCMV Armstrong and Clone 13, with widely disseminated viral replication and viremia that was controlled within 15-30 days, unless CD4 T cells were depleted prior to infection. LCMV-MN responding CD8+ T cells biased differentiation towards the recently described PD1+ CXCR5+ Tim-3lo stem-like CD8+ T cell population (also referred to as T exhausted progenitors, Tpex) that effectuates responses to PD-1 blockade checkpoint inhibition, a therapy that rejuvenates responses against chronic infections and cancer. This subset resembled previously characterized PD1+ TCF1+ stem-like CD8+ T cells by transcriptional, phenotypic, and functional assays, yet was atypically abundant. LCMV-MN may provide a tool to better understand the breadth of immune responses in different settings of chronic antigen stimulation as well as the ontogeny of T exhausted progenitors and the regulation of responsiveness to PD-1 blockade.
Project description:In this study, we examined the role of the transcriptional regulator EGR2 in CD8+ T cell exhaustion during chronic viral infection. We conducted scRNAseq analysis on sorted virus-specific tetramer+ CD8+ T cells isolated at day 20 post-infection with chronic LCMV-Cl13 from either littermate control or EGR2 T cell conditional knock-out mice. Cells were labelled with hashtags and mixed prior to multiplexed analysis. The resulting data demonstrated that the exhausted cell subsets within EGR2 KO CD8+ T cells have an effector-like phenotype, suggesting that EGR2 stabilises the exhausted state.